Observations on Defects in Zone-melting-recrystallized Si Films

We have observed some kinds of defects in unseeded rapid zone-melting-recrystallized(RZMR)Si filmsformed with a RF-induced graphite strip heater system,using cross-section specimen electron microscope.Theobserved defects are subgrain boundaries(SGB),dislocations and microtwins.The most commonly observeddefects are SGB which formed as a result of some orientation differences between adjacent grains during theirrapid self-nucleation growth.Mixed type SGB were frequently observed,although some pure tilt or twist SGBexisted also in the Si films.The rotation angular component around the axis parallel to scanning direction ismuch larger than that around other axes.SGB consist primarily of arrays of dislocation and havecrystallographic angular deviations of one degree or less.During Si film cooling,dislocations and microtwinswere formed due to non-uniform thermal stress.The crystallographic characters of the dislocations in Si filmsare the same as those in common bulk Si single crystals.Their Burgers vectors are b=a/2<110>.Some dis-locations run across the Si film,and the amorphous SiO_2 layers on and underneath the Si film can effectivelyblock the dislocations and prevent them from entering the layers.Microtwins were observed in the Si filmssometimes,the twinning planes being{111}.

Observations on Defects in Zone-melting-recrystallized Si Films

We have observed some kinds of defects in unseeded rapid zone-melting-recrystallized(RZMR)Si films formed with a RF-induced graphite strip heater system,using cross-section specimen electron microscope.The observed defects are subgrain boundaries(SGB),dislocations and microtwins.The most commonly observed defects are SGB which formed as a result of some orientation differences between adjacent grains during their rapid self-nucleation growth.Mixed type SGB were frequently observed,although some pure tilt or twist SGB existed also in the Si films.The rotation angular component around the axis parallel to scanning direction is much larger than that around other axes.SGB consist primarily of arrays of dislocation and have crystallographic angular deviations of one degree or less.During Si film cooling,dislocations and microtwins were formed due to non-uniform thermal stress.The crystallographic characters of the dislocations in Si films are the same as those in common bulk Si single crystals.Their Burgers vectors are b=a/2<110>.Some dis- locations run across the Si film,and the amorphous SiO_2 layers on and underneath the Si film can effectively block the dislocations and prevent them from entering the layers.Microtwins were observed in the Si films sometimes,the twinning planes being{111}.